Immunoconglutinin (IK), antibody to the third component of fixed complement, is stimulated during the course of human and rodent malaria. It has been implicated as an effector antibody in malarial anemia and in recovery from acute plasmodial parasitemia. It is hypothesized that the conglutinating action of IK plays an important role in malarial immunity. Testing this hypothesis, using Plasmodium chabaudi infection in rodents, is the proposed objective. This will be achieved with passively introducing IK and parasite antibody into P. chabaudi infected rats. These intermediates will be given to the rats separately and in combination. Antigens will be prepared from P. chabaudi infected rat erythrocytes and the antibody will be stimulated in rats by the antigen incorporated in adjuvant. IK will be raised in rats by autostimulation. The antigen and antibodies will be purified and concentrated by methods of molecular sieving, affinity chromatography and ultrafiltration. Demonstration that IK is the effector antibody for clearance of parasitemia is anticipated. This concept will be reinforced by utilization of antigen and antibody other than parasite antigen and antibody to serve as the immune complex for fixing C3, binding to infected cells and serve as an intermediate for immunoconglutination by IK. It is anticipated that this research will demonstrate that anti-malarial vaccine must stimulate IK as well as antibody against parasite antigen if it is to be effective.